NECTU head Detective Chief Superintendent Clive Wain said Khadam, from Sheffield, openly supported IS, also known as Daesh.

Mr Wain said his officers reviewed hundreds of hours of video and thousands of social media postings, saying Khadam tweeted up to 20,000 times over one five-week period last year.

He said: " It is clear from the evidence presented that Khadam openly demonstrated support for Daesh and their ideology, using multiple social media accounts to further spread the propaganda of this terrorist organisation.

"Khadam has not disputed posting the information, claiming she did so out of curiosity and the belief that she did not consider it to be terrorist material. Yet this material glorified terrorism and delivered powerful messages, encouraging terrorist acts and calling upon others to kill."

He added: " Khadam was prolific in her use of social media and showed little regard for the consequences of openly sharing deeply disturbing images and material across a number of digital platforms. Much of this material encouraged violent action and was very extreme in the violence it portrayed."

The CTU said officers were alerted by an anonymous tip-off and found Khadam had been using 15 social media profiles for posting extreme material.

It said that o ne of her accounts - with the Twitter handle Jihadi Princess - favourited videos including one that depicted prisoners kneeling in cages in preparation for execution and which went on to show one person being burnt alive in a cage and another having his throat cut.

Another portrayed the use of children by IS, including weapons training and youngsters threatening to kill non-Muslims.

The unit said a nalysis of Khadam's activity on the WhatsApp messaging service showed that she sent a number of IS-produced videos and documents to numerous contacts.

One video by IS leader Abu Bakr al-Baghdad which justified terrorism was sent as a data link, advising contacts to watch it before it was taken down.

Another video was of the murder of a Jordanian pilot who was burned to death.

Mr Wain said his team feared that if Khadam had not been arrested she might have attempted to travel to Syria.

He said: "The reach and influence of social media is vast. Daesh and other groups are increasingly using the internet to encourage support for their objectives and to provoke individuals to carry out attacks in the UK. Therefore, tackling extremist material is important to protect the public and prevent offences that incite or encourage acts of terrorism.

"Today's verdict, I hope, sends out a strong message that actions such as those carried out by Khadam will not be tolerated and ourselves, together with policing colleagues and other partner agencies, will bring those who are breaking the law to justice.

"It is also important to reiterate that our priority is the safety of our communities. We will bring those who have committed a criminal offence before the courts, however we would much prefer to stop people from crossing into a path of criminality."

Khadam was found guilty of 10 counts contrary to Section 2 of the Terrorism Act 2006 - Dissemination of Terrorist Publications.